The elderly often suffer from multiple diseases which require the use of multiple medications often resulting in adverse drug reactions (ADRs). While currently making up 17 percent of the U.S. population, people over 60 years of age account for newly 40 percent of the drug-related hospitalizations and more than half the deaths from ADRS. Most ADRs are extensions of known pharmacological effects and are preventable. The goal of this study is to reduce the rate of ADRs in institutionalized elderly patients by melding an existing computer data base with therapeutic risk-management methodology to develop and implement intervention strategies. The existing network is a pharmacy-based computerized system developed by the Spokane Area Society of Hospital Pharmacists designed to track ADRS. This goal will be accomplished in three steps: 1) The ten most common drug responsible for ADRs in hospitalized elderly patients will be identified as well as the risk factors a&%&ted with ADRs within each of these ten drugs; 2) A hospital pharmacy-based, computerized intervention system that will quickly identify elderly patients at high risk for an ADR from any of the targeted drugs. and recommended preventive strategies for the prescribing physician will be developed and implemented; 3) The impact of this intervention system will be evaluated using a controlled randomized study design. Ibis system will be designed and implemented within the six major hospitals in Spokane, Washington. Patients 60+ years of age, taking one or more of the targeted drugs and having at least one of the identified ADR high risk factors, and hospitalized at one of the six hospitals between January 1, 1992 and December 31, 1993 will be randomly assigned to the intervention group or a control group. The control group will receive usual and customary hospital care. Data will be analyzed to assess the rate of ADRS, cost effectiveness of the system, and average length of stay in an intervention group compared to the control group. After completion of the project, the intervention system and software will be transportable and its use in other institutions and environments will be encouraged.